A touch panel is a touch-sensitive input device. When a user's finger clicks on a graphic button displayed on a touch display device provided with the touch panel, a touch feedback system of the touch panel drives various connected means according to pre-programmed functions, and the display device provided with the touch panel achieves a vivid video effect by means of displayed pictures. So far, the touch panel is a latest input device and represents the simplest, most convenient and natural human-machine interface device.
A touch panel locates a touch point by using an absolute coordinate system, which is featured in that each position coordinate is independent of the preceding position coordinate, thus enabling a user to click any desired position directly. Thus, the touch panel differs from a locating system (such as a mouse) based on a relative coordinate system.
Presently, there are capacitive touch panels and resistive touch panels. Generally, the capacitive touch panel includes a composite glass panel with four layers, where at least one layer of Indium Tin Oxide (ITO) is disposed in the composite glass panel, and the outmost layer of the compound glass panel is a thin Silica glass protective layer. The ITO coating layer is a working layer where a touch electrode layer of the capacitive touch panel is formed. When a user's finger touches the capacitive touch panel, a coupling capacitance is formed between the user and the surface of the capacitive touch panel due to a human body electric field, so that a sensing current flowing through sensing electrodes in the touch electrode layer is changed, and a position of a touch point may be determined from the change of the sensing current, i.e. by comparing magnitudes of the sensing currents.